Regulating means for steam generating plants



May 10, 1938.

K. TOENSFELDT REGULATI'NG MEANS FOR STEAM GENERATING PLANTS Filed Julyl, 1937 Pfg/ I A/R HEATER /A/E COMPRESSOR .5 E P14/94 T01? Afa/2TEA/SFELUT ATORNEY Patented May 10, 1938 PATENT OFFICE REGULATING MEANSFOR STEAM GEN- ERATING PLANTS Kurt Toensfeldt, Port Washington, N. Y.,assignor to Combustion Engineering Company, Inc., New

York, N. Y.

Application July 1, 1937, Serial No. 151,443

5 Claims.

The present invention relates to improvements in means for operatingsteam' generating plants.

The invention is particularly directed to a steam generator which burnsfuel in the furnace under pressure and expands the products ofcombustion over the heating surfaces at relatively high velocities inorder to generate large quantities of steam with relatively smallheating surface. As the pressure of the air for combustion is increasedfor the purpose of generating larger quantities of steam, itscompression becomes a marked pro-` portion of the total output of thesteam generator and enicient means of driving the compressor I should beemployed.

According to the invention the air compressor and preferably also otherauxiliaries for such a steam generator are driven from a steam motor,such as a turbine, through which flows substantially all of the steamproduced by the generator, theI exhaust from the turbine being the steamdelivered from the generator for outside use. Substantially all of theenergy taken from the steam by the turbine for driving the compressorand auxiliaries is` recovered by the compressed air and returned to thefurnace and by the water and fuel from the related pumps when these alsoare driven by the turbine.

The steam turbine is operated in such manner that substantially all ofthe steam produced by the generator flows through the turbine at allnormal loads and only sufficient steam is bypassed to satisfactorilyregulate the turbine speed. The amount of steam which flows to a pointof use without passing through the turbine is regulated by a Valveautomatically operated by suitable mechanism in response to fluctuationsin the pressure of steam in the main steam line at a point beyond theturbine that drives the compressor. This regulating valve may beactuated 4.0 by other means responsive to loads at the point of use,such as steam flow or power output.

In the drawing; Fig. 1 diagrammatically illustrates a steam plantembodying the invention; and .-5 Fig. 2 illustrates a modied form of theinvention.

Referring to the drawing, the steam generator is designated as a wholeby the numeral I0 and is illustrated diagrammatically inasmuch as in anactual embodiment of the invention the steam generator itself may takevarious physical forms. The combustion air has its` pressure increasedby an air compressor II and passes through an air preheater I2 andconduit I3 into the furnace of the generator. Fuel is introduced intothe furnace by a burner or burners I4 which are supplied by a fuel pumpI5 where fluid fuel is employed, or by a suitable means if other fuelsare burned. As illustrated in Figs. 1 and 2, the steam. generator I0includes an economizer I6, generating elements Il, a superheater I8, andin the form shown in Fig. 1, a reheater I9 also.

All of the steam produced in the generator II!` passes therefrom to amain engine, a turbine or other load 2U through a conduit which in Fig.1 comprises the parts 2|, 22, 23, and the parts 2Ia, 22a in Fig. 2.Interposed in this conduit is a small turbine 24 arranged to drive theair compressor II and preferably other auxiliaries such as the fuel pumpI5, boiler feed pump 25 and circulating pump 26.

In the arrangement shown in both gures substantially all of the steamproduced in generator IU passes through the compressor-driving turbine234, only an amount of steam sufficient to regulate the turbine speedpassing tothe point of use Without flowing through the turbine. In Fig.1 piping 21, having a flow regulating valve 28 therein, is connected tothe parts 2l, 22 of the steam conduit that lead respectively to theinlet and from the outlet sides of turbine 24 so as to by` pass partofthe steam around the turbine. In Fig. 2 the piping 30 controlled by avalve 28 per.- mits` some of the steam to pass from the portion 2 Ia ofthe steam conduit that connects with the inlet of turbine 24 to a pointof use without flowing through the turbine. The difference between`Figs. 1 and 2 in this respect is that in Fig. 1 the steam diverted awayfrom the turbine 24 to enable regulation of its speed is returned to thepart 23 of the main steam conduit whereas in Fig. 2 this steam does notre-enter the main steam conduit but may ow directly to a point of usethrough the piping 3U. In both arrangements the amount of steam divertedaway from` the turbine for regulating its speed is automaticallycontrolled` by a device 32 responsive to the pressure of steam in themain steam conduit at a point beyond the turbine 24 and acting throughsuitable mechanism to operate the valve 28. In addition to regulatingthe amount of steam by-passed around or away from the compressor drivingturbine 24 the pressure responsive device 32 may also control andoperate a valve 33 that supplements the regulation of the amount of fuelsupplied to the burners I4 by the fuel pump I5.

In both Figs. 1 and 2 as described above substantially all of the steamproduced in the generator passes through the steam turbine 24 as it newsto the point of use, the valve 28 being opened only enough to by-pass anamount of steam to permit regulation so as to maintain a desiredpressure in the main steam conduit for a certain load. In Fig. 1 thesteam is preferably initially superheated only an amount sufficient toassure dry steam in the turbine 24 and is then passed through thereheater I9 to be superheated to the temperature desired at the point ofuse. In both arrangements the heat drop or energy required to operatethe turbine 24 is substantially all recovered in the compressed airdelivered to generator Ill and in the water and fuel from the relatedpumps. 'I'he heat from the gland leakage of the turbine may be returnedto the boiler feed water by any suitable means, such as a heatexchanger. The pressure responsive device 32, being subject to thepressure of steam at a point beyond the steam turbine, acts to maintaina substantially constant pressure at the point by temporarily furtheropening the valve 28 as the steam pressure in the steam line tends torise in response to a decrease in steam demand. This causes less steamto flow through turbine 24 with the result that the degree of aircompression and rate of fuel supply are reduced and, hence the rate ofsteam generation is decreased. Conversely, the pressure responsivedevice 32 temporarily partly closes the regulating valve 28 to causemore steam to flow through the turbine and increase its speed withconsequent increase in steam generation as the pressure in the mainsteam line falls upon an increase in steam -dem-and. Upon readjustmentof the steam ow and pressure, valve 28 again resumes a normal position.

A regulating valve 33 may be provided in the boiler fuel pump dischargeline, to supplement the regulation of the rate of fuel feed by theturbine 24. This regulating valve 33 is responsive to the pressurechange impulse delivered by the device 32 and functions to throttle orrelease the 'flow of fuel to the generator upon rise or fall,respectively, of the pressure in steam main. A prompt response to loadchanges by the fuel is thereby attained.

A regulating valve 34 may be provided in the boiler feed Water pumpdischarge line, to supplement the regulation of the rate of water feedby the turbine 24. This regulating valve 34 is responsive to the waterlevel in the steam and water separator and is actuated by means such asan expansion type of feed water regulator and the usual connectinglinks. The valve functions to throttle or release the ow of water to thegenerator upon rise or fall, respectively, of the water level in theseparator.

Accordingly the air compressor Il, fuel pump I5, and other auxiliariesare operated substantially in proportion to the steam demand and asubstantially constant pressure of steam is maintained in the main steamconduit while at the same time the energy required to operate theturbine to drive the compressor and other auX- iliaries is recovered inthe compression of the air and also in the fuel and water supplied tothe generator.

In cases where the steam generator is provided with a convection typesuperheater a further advantage is obtained as a result of theemployment of a steam turbine for driving the air compressor. Aconvection type superheater has a dropping temperature characteristic,i. e. the superheat temperature attained falls with reduction in load.The heat drop through the turbine 24 also decreases with reduction inload but to a lesser extent than fluctuations in superheat andaccordingly there is a partial offsetting or compensation for the fallin superheat leaving the generator at normal loads, thereby tendingtoward maintaining a more constant superheat leaving the turbine atthese loads.

What I claim is;

1. In a steam plant including a steam generator, an air compressor andafuel supply means therefor, and wherein the fuel is burned underpressure in the furnace of said generator and the products, ofcombustion are expanded over the heating surfaces of said generator atrelatively high velocities; a conduit for carrying away from thegenerator all of the steam that is generated therein; a steam turbineconnected into said conduit and arranged to operate said air compressor;piping connected to said conduit at the inlet side of said turbine forcarrying part of the steam from said generator to a point of use withoutpassing through said turbine; a valve regulating the ilow of steamthrough said piping; and means responsive to the steam demand in theconduit connecting the turbine and the point of use, controlling saidvalve to Vary the flow through said piping thereby correcting theoperating rate of the turbine to suit the variations in said steamdemand.

2. In a steam plant including a steam generator, an air compressor and afuel supply means therefor, and wherein the fuel is burned underpressure in the furnace of said generator and the products of combustionare expanded over the heating surfaces of said generator at relativelyhigh velocities; a conduit for carrying away from the generator all ofthe steam that is generated therein; a steam turbine connected into saidconduit and arranged to operate said air compressor; piping connected tosaid conduit at the inlet side of said turbine for carrying part of thesteam from said generator to a point of use without passing through saidturbine; a valve regulating the flow of steam through said piping; andmeans, responsive to the load demand at the point of use of the steam,controlling said valve to vary the ow through said piping therebycorrecting the operating rate of the turbine to suit the Variations insaid load demand.

3. In a steam plant including a steam generator, an air compressor and afuel supply means therefor, and wherein the fuel is burned underpressure in the furnace of said generator and the products of combustionare expanded over the heating surfaces of said generator at relativelyhigh velocities; a conduit for carrying away from the generator all ofthe steam that is generated therein; a steam turbine connected into saidconduit and arranged to operate said air compressor; piping connected tosaid conduit at the inlet side of said turbine for carrying part of thesteam from said generator to a point of use without passing through saidturbine; a valve regulating the ow of steam through said piping; andmeans responsive to the pressure of steam in said conduit at a pointbeyond said turbine for controlling said valve to increase the now ofsteam through said piping as said steam pressure rises above apredetermined point and to decrease said flow as said steam pressurefalls below said predetermined pressure.

4. In a power plant having a steam generator, means for supplying fluidor pulverized fuel to the furnace of said generator and a valve or thelike for regulating the fuel supply; a conduit for carrying all thesteam generated in said boiler to a point of use; a turbine interposedin said conduit between said generator and the point of steam use andarranged to drive said fuel supplying means; and means responsive to thepressure of steam in said conduit at a point beyond said turbine forcontrolling said fuel regulating valve to increase the rate of fuelsupply as said pressure falls and decrease said fuel supply rate as saidpressure rises for varying the rate of steam generation oppositely tofluctuations in said pressure.

5. In a power plant including a steam generator, an air compressor and afuel supply means therefor and wherein the fuel is burned under pressurein the furnace of said generator; a conduit for carrying all the steamgenerated in said generator to a point of use; a steam motor interposedin said conduit between said generator and said point of steam use andarranged to drive said air compressor and fuel supply means; pipingconnected to said conduit at the inlet and discharge sides of said steammotor to form a steam by-pass around said motor; a valve for regulatingthe iiow of steam through said bypass; and means responsive to thepressure of steam in said conduit at a point beyond said bypass andcontrolling said valve to increase the flow of steam through saidby-pass as the steam demand falls and decrease said flow as the demandrises for respectively decreasing or increasing the operating rate ofsaid turbine, air compressor and fuel supply means to correspondinglyvary the rate of steam generation in said boiler.

KURT TOENSFELDT.

